Medicaid Payer Status Is Associated with Increased 90-Day Morbidity and Resource Utilization Following Primary Total Hip Arthroplasty

Background: Medicaid payer status has been shown to affect risk-adjusted outcomes and resource utilization across multiple medical specialties. The purpose of this study was to examine resource utilization via readmission rates, length of stay, and total cost specific to Medicaid payer status following primary total hip arthroplasty.

Methods: The Nationwide Readmissions Database (NRD) was utilized to identify patients who underwent total hip arthroplasty in 2013 as well as corresponding “Medicaid” or “non-Medicaid” payer status. Demographic data, 14 individual comorbidities, readmission rates, length of stay, and direct cost were evaluated. A propensity-score-based matching model was utilized to control for baseline confounding variables between payer groups. Following propensity-score matching, the chi-square test was used to compare readmission rates between the 2 payer groups. The relative risk (RR) with 95% confidence interval (CI) was estimated to quantify readmission risk. Length of stay and total cost comparisons were evaluated using the Wilcoxon signed-rank test.

Results: A total of 5,311 Medicaid and 144,814 non-Medicaid patients managed with total hip arthroplasty were identified from the 2013 NRD. A propensity score was estimated for each patient on the basis of the available baseline demographics, and 5,311 non-Medicaid patients were matched by propensity score to the 5,311 Medicaid patients. Medicaid versus non-Medicaid payer status yielded significant differences in overall readmission rates of 28.8% versus 21.0% (p < 0.001; RR = 1.37 [95% CI, 1.28 to 1.46]) and 90-day hip-specific readmission rates of 2.5% versus 1.8% (p = 0.01; RR = 1.38 [95% CI, 1.07 to 1.78]). Mean length of stay was greater in the Medicaid group than in the non-Medicaid group at 4.5 versus 3.3 days (p < 0.0001), as was the mean total cost at $71,110 versus $65,309 (p < 0.0001).

Conclusions: This study demonstrates that Medicaid payer status is independently associated with increased resource utilization, including readmission rates, length of stay, and total cost following primary total hip arthroplasty. Providers may have a disincentive to treat patient populations who require increased resource utilization following surgery. Risk adjustment models accounting for Medicaid payer status are necessary to avoid decreased access to care for this patient population and to avoid financial penalty for physicians and hospitals alike.

Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.